BEGIN;
CREATE SCHEMA test;
CREATE EXTENSION pg_doctest SCHEMA test;
CREATE SCHEMA foo;
-- These tests are correct
CREATE OR REPLACE FUNCTION foo.plus ( a INT, b INT)
RETURNS INT
AS $func$
        --           >>> select        foo.plus(1,1)
  -- 2
-- >>>  SELECT foo.plus(NULL,9)
  -- NULL
        -- >>> SELECt  foo.plus(0,000)
        -- 0
  SELECT a+b;
$func$
  LANGUAGE SQL
;
-- These tests will fail
CREATE OR REPLACE FUNCTION foo.minus ( a INT, b INT)
RETURNS INT
AS $func$
  -- >>> SELECT foo.minus(1,1)
  -- 2
-- >>> SELECT foo.minus(NULL,9)
-- NULL
  SELECT a-b;
$func$
  LANGUAGE SQL
;
SELECT call, passed FROM test.test_schema('foo');
            call             | passed 
-----------------------------+--------
 select        foo.plus(1,1) | t
 SELECT foo.plus(NULL,9)     | t
 SELECt  foo.plus(0,000)     | t
 SELECT foo.minus(1,1)       | f
 SELECT foo.minus(NULL,9)    | t
(5 rows)

SELECT * FROM test.run('foo');
 function_name | passed | failed 
---------------+--------+--------
 foo.plus      |      3 |      0
 foo.minus     |      1 |      1
(2 rows)

DROP SCHEMA foo CASCADE;
NOTICE:  drop cascades to 2 other objects
DETAIL:  drop cascades to function foo.plus(integer,integer)
drop cascades to function foo.minus(integer,integer)
ROLLBACK;